Vibration mill



United States Patent llll 3,545,688

Inventors Goro Oshirna;

lliroshi Hlrata; Kenichiro Tokunaga, Kitakyushu-shi, Japan Appl. No. 736,669 Filed June 13,1968 Patented Dec. 8, 1970 Assignee Kabushiki Kaisha Yaskawa Denki Seisakusho Kitakyushu-shi, Japan a corporation of Japan Priority July 25, 1967 Japan No. 42/ 47,988

VlBRATlON MILL 6 Claims, 8 Drawing Figs.

US. Cl. 241/69, 241/75 Int. Cl. ..B02c 19/00, B02c l7/l0 Field otSearch 241/69, 75,

[56] References Cited UNITED STATES PATENTS l,242,423 10/1917 Cover 24 Ill 79X 2,323,544 7/1943 Kiesskalt 24 l/ l 75X Primary Examiner-Robert C. Riordon Assistant Examiner-Donald G. Kelly Attorney-Ward, McElhannon, Brooks & Fitzpatrick ABSTRACT: The interior of a vibration mill shell with a horizontal axis is provided with side and bottom grinding plates, which transmit vibration to several rings freely moving between and against the grinding plates thereby to accomplish grinding of feed material. a single free round bar ofa diameter substantially less than the inner diameters of the rings being passed through the rings. and perforated plates are interposed between the side and bottom grinding plates to pass ground products of a desired maximum particle size to a discharge outlet.

PATENTEnuec SE70 SHEET 1 (IF 2 FEGJ PATEmEm 8mm SHEEI 2 (IF 2 FIG.4(b)

FIGAW) FIG.5(b)

'vIIIIuI'rI'oN MILL BACKGROUND-OF THE INVENTION This invention relates generally to the field of comminution and more particularly to-a new and improved vibration mill, particularly for coarse and intermediate grinding.

In general, vibration mills have high grinding efficiency and high processing capacity. However, when vibration mills are used for coarse or intermediate grinding, shortening the retention or throughput time of feed materialin the mill shell gives rise to unevenness of ground product particle size in many cases.

Furthermore, since the reducing of relatively large feed material into a fine productin a single operational step requires considerable grinding time, the processing capacity can be-further increased by first carrying out coarse or intermediate grinding and then carrying out fine grinding.

SUMMARY OFTl-IE INVENTION It is an object of the present invention to provide a vibration mill in which the above-ment oned difficulty of obtaining products of uniform size is overcome, and which is highly effective for coarse and intermediate grinding.

Another object of the invention is to provide a vibration mill of simple and durable construction.

A further object of the invention is to provide a vibration mill of the above stated character in various combinations with vibration-generating devices and other vibration mills for finer grinding.

I According to the present invention, briefly summarized, there is provided a vibration mill'characterized by a grinding shell having a feed inlet and a'p'roduct outlet,at least one grinding-surface member provided on the inner side of the shell, a vibration-generating device connected directly to the shell, a plurality of rings adapted to move freely and independently within the shell and causedto vibrate by the grinding surface member, a free round bar passed through the rings and having a diameter substantially less than the inner diameters of the rings, thereby being freetomove therein to impart impact thereto, and at least one perforated structure at a position not contactable by the rings to permit only product particles of desired particle sizes to pass therethrough to the discharge DETAILED DESCRIPTION The example of the vibration mill illustrated in FIGS. 1 and 2 and constituting a preferred embodiment of the invention has a horizontal grinding vessel or shell 1 provided therewithin with a horizontal grinding chamber of octagonal cross section. The shell 1 is provided at its upper part with a material feed inlet 2 connected by way of a flexible tube 3 to the discharge end of a material feed hopper 4; The shell 1 is closed at its ends by end plates, one of which (5) is cut away in FIG. 1 to reveal the interior of the shell. p

The octagonal grinding chamber is provided on its bottom and two vertical sides with spaced-apart grinding-surface plates 7, 6, and 8 which constitute particle inner linings of the grinding chamber and are made of a hard metal such as a highmanganese steel. The sides of the octagonal grinding chamber between these grinding-surface plates 6, 7, and 8 are formed by lattice plates or perforated plates 10 and 11 having perforations through which material of particle sizes smaller than a specific size can pass to be--discharged through a material discharge outlet 9 provided on the bottom of the shell 1. The perforated plates 10 and 11 are disposed farther away from the center of the grinding chamber than the grinding-surface plates 6, 7, and 8 and do not participate directly in the attrition grinding operation.

The grinding chamber contains a plurality of rings 13 disposed loosely therein and lying in planes substantially parallel to each other and substantially perpendicular to the longitudinal axis of the grinding chamber. A round bar 12 of a length slightly less than the inner length of the grinding chamber is passed throughtlie rings 13 and rests freely on the inner surfaces of the rings 13 as indicated in FIGS. 1 and 2. The inner diameter of each ring 13 is substantially greater than the diameter of the roundbar 12, whereby each ring 13 p can move independently relative to the bar 12. The outer diameter of each ring 13 is so selected that, when the ring rests on the bottom grinding-surface material 7, it can contact outlet, feed material introducedthrough the feed inlet being ground principally between the rings and the grinding-surface member. j I

The nature, principle, details, and utility of the invention will be more clearly apparent'frorn the following detailed description with respect to'p'referred embodiments of the invention, when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals. 1'

' BRIEF DESCRIPTION or THE DRAWINGS In the drawings:

FIG. 1 is an elevational view, with a part cut away, showing the essential organization of one example of a vibration mill embodying the invention;

FIG. 2 is a side view showing the arrangement of freely moving rings and an unrestrained round bar loosely passed therethrough in the mill shown inFIG. 1;

FIGS. 3a and 3b are respectively front and side elevational views showing another embodiment of the invention, in which a duplex vibration mill is driven by a single vibration motor;

FIGS. 4a'and 4b are respectively front and side elevational views showing a combination of the vibration mill of the invention with a known vibration mill for finer grinding; and

FIGS. 5a and 5b are respectively front and side elevational views showing a modification of the combination shown in FIGS. 40 and 4b. I I

either of the side grinding-surface plates 6 and 8 and yet not contact either of the perforated plates 10 and 1 1.

Vibration motors 14 and 15 are mounted on respectively opposite lateral sides of the shell 1 and are provided respectively with unbalanced weights 16 and 17 fixed to the rotating parts thereof. Rotation of each of the vibration motors 14 and 15 imparts to the shell. 1 a circular vibration in a vertical plane perpendicular to the longitudinal axis of the shell. When necessary, the two vibration motors 14 and 15 can be caused to rotate in synchronism by a timing belt (not shown).

The shell 1 is mounted on a vibratory support plate 18 which, in turn, is supported in a vibratory manner by springs 20 fixed to a stationary base 19.

The vibration mill of above described essential organization according to the invention operates in the following manner. When the vibration motors 14 and 15 are rotated as indicated by arrows a, a in FIG. 1, the rings 13 contact the grinding-surfa'ce plates 6, 7 and 8 and vibrate.

Then, when a material to be ground is fed through the hopper 4 and feed inlet 2 and enters the grinding chamber as indicated by arrows b, it is ground by grinding action comprising, principally, collision of the material against the rings 13 and grinding-surface plates 6, 7, and 8, milling action between the rings 13 and the plates 6, 7, and 8, and collision and attrition between the material particles themselves. The ground material particles are then discharged out of the machine through the outlet 9 successively in the sequence in which they are reduced to a size permitting their passage through the perforated plates 10 and 11. Material particles remaining on the perforated plates 10 and 11 are immediately hurled upward by the vibration of the shell and are again subjected to the grinding action.

Since the material during this operation thus undergoes motion within the shell 1 which is principally vertical without much movement in the shell longitudinal direction, and the average time of retention of the material within the shell is thereby short, efficient coarse and intermediate grinding can be carried out, and the processing capacity becomes extremely high.

Furthermore, since the round bar 12 is passed through and rides on the rings 13 in a plurality of separate states, uniform impact is imparted to the material being ground. Accordingly, the particle sizes are uniform, which feature is highly desirable for coarse and intermediate grinding. Another desirable feature of the mill according to the invention is that there is almost no possibility of damage to the perforated plates and 11 since the rings 13 contact only the grinding-surface plates 6, 7, and 8 and do not contact the perforated plates 10 and 11.

While the above described vibration mill is of an organization wherein two vibration motors are mounted on respectively opposite. lateral sides of a single-grinding shell, various other organizations are possible within the intended purview of the present invention. For example, as illustrated in FIG. 3, two grinding shells 21a and 21b according to the invention are mounted on respectively opposite lateral sides of a single vibration motor 22 to form an organization of twin shell type, i

the material ground in the two shells 21a and 21b and passing through their respective perforated plates being discharged through a common discharge outlet 9a.

In still another embodiment of the invention as illustrated in FIG. 4, a vibration mill shell 23 having raw material overflow chutes 23a is mounted on the top of a support structure 25 which is supported on springs 25a and supports vibration motors 24a and 24b in tandem arrangement below the mill shell 23. The support structure further supports a vibration mill 26 which may be of any conventional type below the vibration motors 24a and 24b. Accordingly, there is formed an organization of two-stage type wherein relatively coarse or intermediate particles of the material produced by the vibration mill of the invention are conducted directly into the lower mill to be finely ground.

In a modification as illustrated in FIG. 5 of the vibration mill combination shown in FIG. 4, the feed material is introduced into the middle part of the upper vibration mill 27 according to the invention and caused to move, as it is ground toward the two longitudinal ends of the shell and be discharged therefrom into the two longitudinal ends of the lower vibration mill 29 of conventional type disposed below a vibration motor 28. The material then travels, as it is ground, toward the middleof the mill 29 to be discharged therefrom through a single discharge outlet.

By the organization as described above, the present invention provides a vibration mill which is capable of accomplishing coarse and intermediate grinding with high efficiency, and which, moreover, has extremely high durability.

The vibration mill according to the invention has been found to be highly effective in the grinding of a'wide range of materials, examples of which are ores, minerals, and stones in general (limestone, silica, etc.), scrap brick, scrap glass, slags, and scrap ferrites. In addition, the vibration mill of the invention can be used for other classes of substances such as certain chemicals and food products.

While the particle sizes of the feed material and the product vary with the material to be ground and the grinding requirements, the vibration mill of the invention is most effective in grinding feed materials of an average size of approximately 80 mm. to produce particles of 2 mm. or smaller size when used as a single-stage mill. When the mill of the invention is used in combination with a conventional vibration mill as described above, the resulting two-stage mill is capable of grinding feed materials of approximately 80-mrn. size to produce particles of approximate ZOO-mesh, 50 percent, size.

In one example of actual practice, a vibration mill of the invention used singly and driven by a l5-kw. motor reduced silica of 60-mm. particles size to a product of 4 mm. and smaller size at a rate of 3 metric tons per. hour. In another example, a vibration mill of the invention combined with an ordinary mill and driven by a lS-kw. motor reduced limestone of 60-min. size to a product of 4 mm. and smaller size at a rate of 1 metric toriger l our.

e vibration mill of the mventlon can be used for either wet or dry operation. When this vibration mill is used singly, its grinding performance under wet operation is approximately 1.5 times that under dry operation.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

We claim:

I. A vibration mill comprising: a grinding shell l having a feed material inlet 2 and a ground-product discharge outlet 9; at least one grinding-surface member 6, 7, 8 provided on the inner side of said shell; vibration-generating means 14, 15 to impart vibration to the shell; grinding-intermediation means including a plurality of rings 13 adapted to move freely and independently within the shell and caused to vibrate by said vibration transmitted thereto by the grinding-surface member,

and at least one perforated structure 10, 11 disposed within the shell at a positionradially outwardly of a circumference corresponding to the maximum radial displacement achievable by the rings and adapted to permit only particles of ground material of predetermined particle sizes to pass therethrough and thence be discharged through said discharge outlet, feed material introduced through said inlet being ground principally between the rings and the grinding-surface member.

2. The vibration mill as claimed in claim 1 in which the grinding shell has a horizontal longitudinal axis, relative to which the axes of the rings are'approximately parallel, and an interior constituting a grinding chamber of a cross section which is polygonal in at least the bottom and side parts thereof, and the grinding-surface member comprises at least longitudinally extending side and bottom plates fixed respectively to the lateral sides and bottom of said chamber, two perforated structures being interposed respectively between the side plates and the bottom plate.

3L The vibration mill as claimed in claim 2 in which the vibration-generating means comprises at least two vibration "motors mounted on the grinding shell, and the grinding shell is mounted on a vibratory support plate which is supported through elastic members by a stationary base.

4. The vibration mill as claimed in claim 2 which is in integral combination with at least one other vibration mill, the vibration-generating means comprising at least two vibration motors connected to all vibration mills, said mills being mounted on a common, vibratory support plate which is supported through elastic members by a stationary base, and the discharge outlets of all mills being joined at a common outlet.

5. The vibration mill as claimed in claim 2 which is in integral combination with a second vibration mill for finer grinding, the discharge outlet of the f rst named mill being connected directly to the feed inlet of the second mill, and the two mills and the vibration-generating means are connected to form an integral structure mounted through elastic members on a stationary base.

6. The vibration mill as claimed in claim 1, wherein a bar is passed freely through the rings and has a diameter smaller than the inner diameters of the rings. 

